U.S. patent application number 16/327029 was filed with the patent office on 2019-06-27 for keratoprosthesis apparatuses, systems, and methods.
The applicant listed for this patent is Massachusetts Eye and Ear Infirmary. Invention is credited to Eleftherios Ilios Paschalis.
Application Number | 20190192281 16/327029 |
Document ID | / |
Family ID | 61246264 |
Filed Date | 2019-06-27 |
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United States Patent
Application |
20190192281 |
Kind Code |
A1 |
Paschalis; Eleftherios
Ilios |
June 27, 2019 |
KERATOPROSTHESIS APPARATUSES, SYSTEMS, AND METHODS
Abstract
The present disclosure relates to keratoprosthesis apparatuses
comprising a flexible backplate and methods of manufacturing and
implanting the new keratoprosthesis apparatuses. The
keratoprosthesis apparatuses include a circular backplate composed,
at least in part, of a titanium alloy. The circular backplate
includes an annular rim portion having a central aperture extending
therethrough. A plurality of tabs is positioned along the annular
rim portion and extend radially inwardly into the aperture. A
plurality of flexible appendages extends radially outwardly from
the annular rim portion and is positioned along the annular rim
portion at locations corresponding to the plurality of tabs.
Inventors: |
Paschalis; Eleftherios Ilios;
(Quincy, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Massachusetts Eye and Ear Infirmary |
Boston |
MA |
US |
|
|
Family ID: |
61246264 |
Appl. No.: |
16/327029 |
Filed: |
August 24, 2017 |
PCT Filed: |
August 24, 2017 |
PCT NO: |
PCT/US17/48462 |
371 Date: |
February 21, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62378986 |
Aug 24, 2016 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2220/0008 20130101;
A61F 2/142 20130101; A61F 2/16 20130101 |
International
Class: |
A61F 2/14 20060101
A61F002/14 |
Claims
1. A keratoprosthesis apparatus comprising: a circular backplate
composed, at least in part, of a titanium alloy, wherein the
circular backplate includes an annular rim portion having a central
aperture extending therethrough; a first plurality of tabs
positioned along the annular rim portion and extending radially
inwardly into the aperture; and a plurality of flexible appendages
extending radially outwardly from the annular rim portion and
positioned along the annular rim portion at locations corresponding
to the first plurality of tabs, wherein the plurality of flexible
appendages is configured to provide leverage to pivot the first
plurality of tabs outwardly.
2. The keratoprosthesis apparatus of claim 1, the titanium allow
includes a super elastic alloy.
3. The keratoprosthesis apparatus of claim 1, wherein the titanium
alloy comprises a shape memory alloy.
4. The keratoprosthesis apparatus of claim 3, wherein the titanium
alloy comprises a titanium nickel alloy.
5. The keratoprosthesis apparatus of claim 1, further comprising an
optical stem including a curvilinear crown portion and a neck
portion extending from the curvilinear crown portion, wherein the
neck portion comprises an annular ridge having a smaller diameter
than the neck portion, and wherein the circular backplate is
coupled to the optical stem via engagement of the plurality of tabs
in the ridge of the neck portion of the optical stem.
6. The keratoprosthesis apparatus of claim 5, further comprising a
coaxial sleeve positioned about the neck portion of the optical
stem, wherein the coaxial sleeve includes a sleeve ridge
corresponding to the annular ridge, and wherein the circular
backplate is coupled to the optical stem via engagement of the
plurality of tabs in the sleeve ridge.
7. The keratoprosthesis apparatus of claim 6, wherein the sleeve
comprises titanium.
8. The keratoprosthesis apparatus of claim 1, wherein one or more
tabs in the first plurality of tabs include a curved edge.
9. The keratoprosthesis apparatus of claim 1, wherein the circular
backplate is configured in a curvilinear profile.
10. The keratoprosthesis apparatus of claim 1, further comprising a
second plurality of appendages extending radially outwardly from
the annular rim portion and positioned along the annular rim
portion at locations intermediate to the first plurality of
tabs.
11. A method of assembling a keratoprosthesis apparatus, the method
comprising: obtaining a circular backplane having a plurality of
tabs positioned along and extending radially inwardly from an
annular rim portion of the circular backplate, the plurality of
tabs defining a space between them; moving the plurality of tabs by
flexing a plurality of flexible appendages extending radially
outwardly from the annular rim portion and positioned along the
annular rim portion at locations corresponding to the plurality of
tabs, whereby the plurality of tabs pivot about the annular rim
portion so as to increase a diameter of a space between the
plurality of tabs; inserting a neck portion of an optical stem
including a curvilinear crown portion into the space between the
plurality of tabs so as to position an annular ridge in the neck
portion having a smaller diameter than the neck portion adjacent
the plurality of tabs; and releasing the plurality of flexible
appendages to reduce the diameter of the space between the
plurality of tabs to engage the plurality of tabs in the ridge.
12. The method of claim 11, further comprising inserting a sleeve
about the neck portion of the optical stem so that the sleeve is
positioned on the neck portion between the circular back plate and
the neck portion of the optical stem.
13. A method of assembling a keratoprosthesis apparatus, the method
comprising: inserting a neck portion of an optical stem including a
curvilinear crown portion into a space between a plurality of tabs
positioned along and extending radially inwardly from an annular
rim portion of a circular backplate composed of a shape memory
alloy and having a plurality of flexible appendages extending
radially outwardly from the annular rim portion and positioned
along the annular rim portion so as to position an annular ridge
having a smaller diameter than the neck portion adjacent the
plurality of tabs; and inwardly flexing the plurality of tabs to
reduce a diameter of the space between the plurality of tabs by
actuating the shape memory alloy to engage the plurality of tabs in
the ridge.
14. The method of claim 13, wherein causing the plurality of tabs
to flex inwardly by actuating the shape memory alloy includes
changing the temperature of the circular backplate.
15. A keratoprosthesis apparatus comprising: a circular backplate
composed, at least in part, of a titanium alloy, wherein the
circular backplate includes an annular rim portion having a central
aperture extending therethrough; a plurality of tabs positioned
along the annular rim portion and extending radially inwardly into
the aperture; and a plurality of flexible appendages extending
radially outwardly from the annular rim portion and positioned
along the annular rim portion; and an optical stem including a
curvilinear crown portion and a neck portion extending from the
curvilinear crown portion, wherein the neck portion comprises an
annular ridge having a smaller diameter than the neck portion, and
wherein the circular backplate is coupled to the optical stem via
engagement of the plurality of tabs in the ridge of the neck
portion of the optical stem.
16. The keratoprosthesis apparatus of claim 15, further comprising
bi-lateral extensions extending from a radially outer end of a
flexible appendage in the plurality of flexible appendages.
17. The keratoprosthesis apparatus of claim 16, wherein the
bilaterally extensions are curvilinear.
18. The keratoprosthesis apparatus of claim 17, wherein the
plurality of tabs include a curved edge configured to engage the
annular ridge in the neck portion.
Description
RELATED APPLICATION
[0001] The present application claims priority to U.S. Provisional
Patent Application No. 62/378,986, filed on Aug. 24, 2016, entitled
"KERATOPROSTHESIS APPARATUSES, SYSTEMS, AND METHODS," which
application is incorporated herein by reference in its
entirety.
TECHNICAL FIELD
[0002] The present application relates generally to the field of
keratoprosthesis systems.
BACKGROUND
[0003] The Boston Keratoprosthesis is a commonly used artificial
cornea that is utilized in a broad array of corneal conditions not
amenable to standard corneal transplantation. The Boston
Keratoprosthesis artificial cornea device is designed like a collar
button, with a plastic stem and a backplate supporting the donor
corneal tissue. The Boston Keratoprosthesis is generally
implemented with a donor cornea having a central hole to mount the
optical stem. The backplate is placed at the posterior surface of
the cornea (behind the Descemet membrane and epithelium) and
provides mechanical support to the stem and graft. After assembly,
the graft cornea is sutured to the host cornea in the same fashion
that a penetrating keratoplasty (PK) procedure is performed.
[0004] Recent advancements in the Boston Keratoprosthesis
artificial cornea devices have allowed the adaptation of titanium
as a backplate material, which resulted in marked improvement in
retroprosthetic membrane formation and has enhanced the device by
providing higher tensile strength, corrosion resistance,
bio-inertness, ductility, and lightness (for example, 4.5
g/cm.sup.3). However, postoperative complications such as corneal
graft melting, necrosis, infection, retroprosthetic membrane,
vitritis, endophthalmitis, retinal detachment, and glaucoma remain
a reality, especially in patients having autoimmune and chemical
burns. The inability of the corneal graft tissue to adhere to a
plastic stem formed of a material such as polymethyl methacrylate
(PMMA) prevents bio-integration and compromises physical barriers.
For example, non-adherence can have an adverse impact on the
corneal epithelium and the Descemet membrane by increasing the risk
of pathogen entry into the eye. Additionally, a lack of tissue
bio-integration prolongs wound healing and promotes low-grade
subclinical inflammation, which might have deleterious effects to
corneal grafts and the eye. In addition, aqueous leaks through the
stem can cause hypotony and retinal detachment, which, if not
promptly treated, can result in permanent vision loss.
SUMMARY
[0005] The inventors have discovered that a keratoprosthesis
apparatus that includes a flexible backplate can be advantageously
implanted in the eye without disrupting the corneal endothelium.
Some benefits of an intact corneal endothelium include decreased
risk of infection, decreased risk of graft failure, and decreased
risk of glaucoma. Accordingly, various embodiments disclosed herein
provide keratoprosthesis apparatuses and systems having a flexible
backplate, and methods of using these apparatuses and systems that
can be implanted in the eye without disrupting the corneal
endothelium.
[0006] Various embodiments provide a keratoprosthesis apparatus
including a circular backplate composed, at least in part, of a
titanium alloy, wherein the circular backplate includes an annular
rim portion having a central aperture extending therethrough, a
plurality of tabs positioned along the annular rim portion and
extending radially inwardly into the aperture, and a plurality of
flexible appendages extending radially outwardly from the annular
rim portion and positioned along the annular rim portion at
locations corresponding to the plurality of tabs. The plurality of
flexible appendages is configured to provide leverage to pivot the
plurality of tabs outwardly.
[0007] In some implementations, the titanium alloy includes a
titanium nickel alloy or a shape memory material such as
nitinol.
[0008] In some implementations, the titanium allow includes a super
elastic alloy.
[0009] In some implementations, the keratoprosthesis apparatuses
include an optical stem including a curvilinear crown portion and a
neck portion extending from the curvilinear crown portion, wherein
the neck portion comprises an annular ridge having a smaller
diameter than the neck portion, and wherein the circular backplate
is coupled to the optical stem via engagement of the plurality of
tabs in the ridge of the neck portion of the optical stem.
[0010] In some implementations, the keratoprosthesis apparatuses
include a coaxial sleeve positioned about the neck portion of the
optical stem. The coaxial sleeve can include a sleeve ridge
corresponding to the annular ridge. The circular backplate can be
coupled to the optical stem via engagement of the plurality of tabs
in the sleeve ridge. The sleeve may be fitted to the optical stem
prior to backplate engagement. Alternatively, the backplate can be
fitted to the sleeve and then the sleeve with the backplate is
fitted to the optical stem as one body.
[0011] In some implementations, the sleeve is composed of titanium.
In additional implementations, one or more tabs in the plurality of
tabs include a curved edge. In some implementations, the circular
backplate is configured in a curvilinear profile. In other
implementations, the circular backplate is configured for elastic
deformation.
[0012] In some implementations, an additional plurality of flexible
appendages extends radially outwardly from the annular rim portion
and is positioned along the annular rim portion at locations
intermediate to the plurality of tabs.
[0013] Various embodiments provide methods of assembling a
keratoprosthesis apparatus. The methods include obtaining a
circular backplane having a plurality of tabs positioned along and
extending radially inwardly from an annular rim portion of the
circular backplate. The plurality of tabs define a space between
them The method includes moving the plurality of tabs by flexing a
plurality of flexible appendages extending radially outward from
the annular rim portion and positioned along the annular rim
portion at locations corresponding to the plurality of tabs. This
causes the plurality of tabs to pivot about the annular rim portion
so as to increase a diameter of the space between the plurality of
tabs. The methods include inserting a neck portion of an optical
stem including a curvilinear crown portion into the space between
the plurality of tabs so as to position an annular ridge in the
neck portion having a smaller diameter than the neck portion
adjacent the plurality of tabs. The methods can further include
releasing the plurality of flexible appendages to reduce the
diameter of the space between the plurality of tabs to engage the
plurality of tabs in the ridge.
[0014] In some implementations, the methods include inserting a
sleeve about the neck portion of the optical stem so that the
sleeve is positioned on the neck portion between the circular back
plate and the neck portion of the optical stem.
[0015] Various embodiments provide methods of assembling a
keratoprosthesis apparatus. The methods include inserting a neck
portion of an optical stem including a curvilinear crown portion
into a space between a plurality of tabs positioned along and
extending radially inwardly from an annular rim portion of a
circular backplate composed of a shape memory alloy and having a
plurality of flexible appendages extending radially outward from
the annular rim portion and positioned along the annular rim
portion so as to position an annular ridge having a smaller
diameter than the neck portion adjacent the plurality of tabs; and
inwardly flexing the plurality of tabs to reduce a diameter of the
space between the plurality of tabs by actuating the shape memory
alloy to engage the plurality of tabs in the ridge.
[0016] Various embodiments provide a keratoprosthesis apparatus
including a circular backplate composed, at least in part, of a
titanium alloy. The circular backplate includes an annular rim
portion having a central aperture extending therethrough. The
keratoprosthesis apparatus includes a plurality of tabs positioned
along the annular rim portion and extending radially inwardly into
the aperture. The keratoprosthesis apparatuses include a plurality
of flexible appendages extending radially outwardly from the
annular rim portion and positioned along the annular rim portion.
The keratoprosthesis apparatuses include an optical stem including
a curvilinear crown portion and a neck portion extending from the
curvilinear crown portion. The neck portion includes an annular
ridge having a smaller diameter than the neck portion. The circular
backplate is coupled to the optical stem via engagement of the
plurality of tabs in the ridge of the neck portion of the optical
stem.
[0017] In some implementations, the appendages include bi-lateral
extensions extending from a radially outer end of a flexible
appendage in the plurality of flexible appendages.
[0018] In some implementations, the bilateral extensions are
curvilinear.
[0019] In some implementations, the plurality of tabs include a
curved edge configured to engage the annular ridge in the neck
portion.
[0020] All combinations of the foregoing concepts and additional
concepts discussed in greater detail below (provided such concepts
are not mutually inconsistent) are part of the inventive subject
matter disclosed herein. In particular, all combinations of claimed
subject matter appearing at the end of this disclosure are part of
the inventive subject matter disclosed herein. Terminology
explicitly employed herein that also may appear in any disclosure
incorporated by reference should be accorded a meaning most
consistent with the particular concepts disclosed herein.
[0021] For the purpose of this disclosure, the term "coupled" means
the joining of two members directly or indirectly to one another.
Such joining may be stationary or moveable in nature. Such joining
may be achieved with the two members or the two members and any
additional intermediate members being integrally formed as a single
unitary body with one another or with the two members or the two
members and any additional intermediate members being attached to
one another. Such joining may be permanent in nature or may be
removable or releasable in nature.
[0022] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, suitable methods and materials are described below. All
publications, patent applications, patents, and other references
mentioned herein are incorporated by reference in their entirety.
In case of conflict, the present specification, including
definitions, will control. In addition, the materials, methods, and
examples are illustrative only and not intended to be limiting.
[0023] Other features and advantages will be apparent from the
following detailed description, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The skilled artisan will understand that the drawings
primarily are for illustrative purposes and are not intended to
limit the scope of the inventive subject matter described herein.
The drawings are not necessarily to scale; in some instances,
various aspects of the inventive subject matter disclosed herein
may be shown exaggerated or enlarged in the drawings to facilitate
an understanding of different features. In the drawings, like
reference characters generally refer to like features (e.g.,
functionally similar and/or structurally similar elements).
[0025] FIG. 1 is a top view of an example of a keratoprosthesis
apparatus as described herein.
[0026] FIG. 2 is a side view of an example of an optical stem as
described herein.
[0027] FIGS. 3A-3C are views of the keratoprosthesis apparatus of
FIG. 1 coupled to the optical stem of FIG. 2.
[0028] FIG. 4 is a flow diagram of an example of a method of
forming a keratoprosthesis apparatus.
[0029] FIG. 5 is a flow diagram of another example of a method of
forming a keratoprosthesis apparatus.
[0030] FIGS. 6A-6E are schematic diagrams that illustrate a process
for implanting a keratoprosthesis apparatus.
[0031] FIGS. 7A-7B are photographic representations of an implanted
keratoprosthesis apparatus at 1 week and 10 months after
implantation.
[0032] FIG. 7C is a photomicrographic representation of an eye in
vivo using optical coherence tomography.
[0033] FIG. 8 is a photographic representation of an implant with
the opacity between the lens and the Descemet's membrane removed
using membranectomy.
[0034] FIG. 9 is a photographic representation of the
keratoprosthesis after being implanted for 1 year.
[0035] FIG. 10 is a schematic diagram that shows another example of
a keratoprosthesis apparatus.
[0036] FIG. 11 is a schematic representation of a stress-strain
simulation of the keratoprosthesis apparatus of FIG. 10.
[0037] The features and advantages of the inventive concepts
disclosed herein will become more apparent from the detailed
description set forth below when taken in conjunction with the
drawings.
DETAILED DESCRIPTION
[0038] Following below are more detailed descriptions of various
concepts related to, and exemplary embodiments of, inventive
systems, methods, and components related to a keratoprosthesis.
[0039] Deep anterior lamellar keratoplasty (DALK) is a preferred
surgical procedure for corneal diseases that do not affect the
endothelium. DALK has become a preferred surgical procedure for
corneal diseases that do not involve the endothelium and for
surgery in patients that do not necessitate full thickness
transplantation. The big bubble technique and advancements in
microkeratomes/femtosecond lasers have revolutionized DALK surgery
and provide distinct advantages over penetrating keratoplasty, such
as better wound healing, reduced intraocular inflammation,
increased safety, and decreased rejection rate. Various embodiments
of the present invention provide a keratoprosthesis apparatus that
is suitable for implanting using a DALK technique.
[0040] Keratoprostheses
[0041] To achieve this goal various implementations disclosed
herein provide a keratoprosthesis apparatus made with a flexible
titanium backplate, as shown in FIG. 1 that can be implanted
intracorneally in a donor graft using a DALK technique described in
further detail in FIGS. 6A-E.
[0042] FIG. 1 is a top view of a flexible backplate 100. The
flexible backplate is generally composed of a titanium alloy, which
can include, but is not limited to, a nickel titanium alloy and/or
a nitinol titanium alloy. In some implementations, the flexible
backplate is composed of a super elastic alloy. In some
implementations, the titanium alloy can include 55% titanium and
45% nickel. In some implementations, the titanium alloy can have a
Young's modulus in the range of 20-200 GPa (austenite), 10-100 GPa
(martensite). The flexible backplate 100 includes an annular rim
portion 101. A plurality of tabs 102 extend radially inward into an
optical aperture 105 formed by the annular rim portion 101. The
tabs 102 include a curved inner edge 106. As discussed further
herein, the inner edge 106 of the tabs 102 is configured for
engagement with a round neck portion of an optical stem. The
flexible backplate 100 also includes a plurality of flexible
appendages 103 that extend radially outward from the annular rim
portion 101. The flexible appendages 103 provide support for a
donor corneal graft or corneal tissue. The flexible appendages 103
are positioned along the rim a locations corresponding to the tabs
102 so that the flexible appendages 103 can be used as levers to
cause the tabs 102 to pivot outward so that a space positioned
between the tabs can be varied.
[0043] As described in further detail herein, the variation of the
space is used for coupling the flexible backplate 100 to an optical
stem and in particular to a groove formed in the stem. The position
of the tabs may be varied by manually flexing the flexible
appendages 103 or by actuating the shape memory of the flexible
backplate 100 in implementations where the flexible backplate 100
is composed of a shape memory material. The flexible backplate 100
may be formed into the shape and profile illustrated in FIG. 1 via
processes, such as laser cutting, photo etching, and/or
stamping.
[0044] FIG. 2 is a side view of an optical stem 202. The optical
stem 202 is configured in a manner similar to a collar button. The
optical stem 202 can be composed of a plastic material such as
polymethyl methacrylate (PMMA) and can be translucent. The optical
stem 202 includes a curvilinear crown portion 201 that generally
has a larger diameter than a neck portion 203 extending from the
crown portion 201. The neck portion 203 is configured to receive a
donor corneal graft or corneal tissue having an aperture formed
therein. The aperture formed in the donor corneal graft is
generally approximately 3 mm in dimeter. Accordingly, the neck
portion 203 is also generally approximately 3 mm in dimeter. As
discussed further herein, in some embodiments, the neck portion 203
may be fitted with a coaxial titanium sleeve. In such cases, the
outer diameter of the combined neck portion 203 and the sleeve
substantially correspond to the aperture in the donor corneal graft
or corneal tissue. The neck portion 203 includes a groove or
annular ridge 204 formed therein. The annular ridge 204 is
configured to receive the tabs 102 of the flexible backplate 100 to
engage and hold the backplate 100 on the optical stem 202.
Accordingly, the annular ridge 204 has a smaller diameter than the
neck portion 203. The diameter of the annular ridge 204 generally
corresponds to the diameter of a space between the tabs 102, when
the tabs 102 are in an unbiased position. The annular ridge 204 is
positioned toward a posterior end of the neck portion 203.
[0045] FIGS. 3A-3C are views of a keratoprosthesis apparatus 300
including the flexible backplate 100 of FIG. 1 coupled to the
optical stem 202 of FIG. 2. FIG. 3A is a top view. FIG. 3B is a
bottom view. FIG. 3C is a side view. As shown in FIG. 3C, the
optical stem 202 can be fitted with a titanium sleeve 301
positioned about the neck portion 203 of the optical stem 202. The
sleeve 301 is positioned on the neck portion 203 between the
flexible back plate 100 and the optical stem 202. As shown in FIG.
3C, the flexible backplate 100 can have a curvilinear profile and
can have a radius of curvature including, but not limited to, of
6.8 mm. As described herein, the flexible backplate 100 can be
composed of a nitinol material, which can include a super elastic
nitinol or a shape memory nitinol. In both materials, the permanent
convex shape providing the curvilinear profile is given by high
temperature (for example .about.540 C) annealing of the nitinol
backplate 100 into a mold with the desired curvature. This shape is
remembered. In the super elastic nitinol, the material is operated
in its austenite phase. The flexible appendages 103 bend and return
to the original shape. In the shape memory nitinol, there is a
transition temperature between the deformable martensite phase and
the flexible austenite phase. In the martensite phase, the shape
memory nitinol material will fold and remain folded. Once the
temperature exceeds the transformation temperature (for example
35.degree. C.), the nitinol will enter into the austenite phase and
become flexible, hence returning to the original shape.
[0046] Methods of Making the Keratoprosthesis Described Herein
[0047] FIG. 4 is a flow diagram of a method of forming a
keratoprosthesis apparatus. The keratoprosthesis apparatus formed
by method 400 may be formed using a flexible backplate 100 composed
at least in part, of a titanium alloy. At 401, the flexible
backplate 100 is flexed from a first position to a second position.
In the first position, the space between the tabs 102 of the
backplate 100 have a first diameter. In the first position, an
unbiased position, the backplate 100 can have a curvilinear
profile. In the second position, the space between the tabs 102 of
the backplate 100 have a second diameter that is larger than the
first diameter. The first diameter corresponds to the diameter of
the ridge 204 of the neck portion 203. The second diameter is
slightly larger than the diameter of the coaxial collar and neck
portion 203. At 402, the neck portion 203 of the optical stem 202
is inserted in the space between the tabs 102 and the annular ring
101 of the backplate 100. At 402, the neck portion 203 is inserted
until the ridge 204 in the neck portion 203 is adjacent the tabs
102. In some implementations, a sleeve such as sleeve 301 is
inserted about the neck portion 203 and a donor corneal graft or
corneal tissue is positioned about the neck portion 203, before the
neck portion 203 is inserted in the space between the tabs 102. At
403, the appendages 103 are released so that the backplate 100
returns to the unbiased position. Upon release of the appendages at
403, the space between the tabs 102 of the backplate 100 return to
the first diameter and the tabs 102 are engaged in the ridge
204.
[0048] FIG. 5 is a flow diagram of another method of forming a
keratoprosthesis apparatus. The keratoprosthesis apparatus formed
by method 500 may be formed using a flexible backplate 100 composed
at least in part, of a shape memory alloy. At 501, the neck portion
203 of the optical stem 202 is inserted in the space between the
tabs 102 and the annular ring 101 of the backplate 100 until the
ridge 204 in the neck portion 203 is adjacent the tabs 102. At 502,
the shape memory material of the flexible backplate 100 is then
actuated (either moved or released) so that the flexible backplate
100 moves to a second shape where the diameter between the tabs 102
is smaller than the diameter between the tabs 102 before actuation.
During this actuation, the tabs 102 are engaged in the ridge 204.
The shape memory material can be actuated via a change in
temperature.
[0049] Methods of Implanting Keratoprosthesis Apparatuses
[0050] FIG. 6 illustrates a process for implanting a
keratoprosthesis apparatus using a DALK technique. As shown in FIG.
6A, a section 601 (approximately 8 mm) of an anterior cornea 602 is
removed. As shown in FIG. 6C, a donor cornea 603 configured to fit
in the opening 604 (FIG. 6C) left of the anterior cornea 602 will
receive a 3 mm central hole 606 and a PMMA optical stem 202 will be
inserted and secured to the donor cornea 603 by the flexible
titanium backplate 100 (FIG. 6D). As shown in FIG. 6E the PMMA stem
202 will be positioned on the surface of Descemet membrane, without
penetrating into the anterior chamber. This surgical approach is
not penetrating, thus minimizing the complications of a mesoimplant
and simplifies the post-operative care. In addition, the flexible
titanium backplate 100 can be implemented in regular Boston
Keratoprosthesis implantation, providing corneal flexibility
together with biomechanics support, thus resuming the physiological
micro movement of the cornea.
[0051] FIGS. 7A-7C show an implanted keratoprosthesis apparatus.
The keratoprosthesis apparatus 300 is illustrated implanted in a
rabbit eye 801 in FIG. 7A. The keratoprosthesis apparatus 300 was
implanted in New Zealand white rabbits using DALK. An allograft
donor cornea was used as a tissue carrier. FIG. 7A shows the
implanted keratoprosthesis apparatus 300 one-week post-operation.
FIG. 7B shows the implanted keratoprosthesis apparatus 300 ten
months post-operation. The keratoprosthesis apparatus 300 was well
tolerated by the eye 801 and caused minimal corneal inflammation
and neovascularization.
[0052] FIG. 7C illustrates measurements taken in vivo via optical
coherence tomography. At 10 months, the intraocular pressure (IOP)
was normal (<18 mmHg) and similar to baseline (i.e., 17 mmHg),
while the anterior chamber architecture was maintained. FIG. 7C
shows that the corneal-iris angle (designated by "Angle" in the
image) is open, allowing aqueous humor flow to the trabecular
meshwork. The pupillary margin is positioned posteriorly to the
cornea without signs of traction towards the graft junction.
[0053] The eye 801 developed some degree of retro-prosthetic
membrane, which was loosely attached to the posterior surface of
the optical stem 202. Successful removal of the retro-prosthetic
membrane was performed through the clear cornea using a 30 G
needle.
[0054] FIG. 8 shows the keratoprosthesis after being implanted for
1 year in the rabbit eye. As demonstrated in FIG. 8, the allograft
cornea appears transparent and well accepted by the host eye 801.
The keratoprosthesis apparatus 300 is well retained, and the graft
is griped tightly around the titanium sleeve 301 and optical stem
202. The anterior chamber architecture of eye 801 is intact with
normal TOP (pre-op 17 mmHg, 1-year post-op 16 mmHg).
[0055] FIG. 9 shows the opening of the opaque Descemet's membrane
behind the lens using membranotomy. Some opacity between the lens
and the Descemet's membrane was formed after the surgery. The
opacity in the membrane was removed using membranotomy using a 30 G
needle that performed a crosscut of the Descemet's membrane.
Preventative membranectomy can also be performed either immediately
after implantation of the device, or at a later quiet stage.
Alternatively, a YAG laser may be used to perform the
membranotomy.
[0056] FIG. 10 shows another example of a flexible backplate for a
keratoprosthesis apparatus. Flexible backplate 1000 includes a
plurality of flexible appendages 1003 positioned about annular rim
portion 1001. The flexible appendages 1003 provide support for a
donor corneal graft or corneal tissue. A plurality of tabs 1002
having curved inner edges 1006 are positioned about the annular rim
portion 1001 of the flexible backplate 1000. The inner edge 1006 of
the tabs 1002 are configured for engagement with a round neck
portion of an optical stem.
[0057] The flexible backplate 1000 also includes intermediate
flexible appendages 1013 that provide extra tissue support for a
donor corneal graft when a keratoprosthesis apparatus formed with
the flexible backplate 1000 is implanted. The flexible backplate
1000 is generally composed of a titanium alloy, which can include,
but is not limited to, a nickel titanium alloy and/or a nitinol
titanium alloy. While the flexible backplate 1000 is illustrated
with a nominal diameter of 2.8 mm between the curved edges 1006 of
the tabs, a nominal diameter of 6.6 mm about the intermediate
flexible appendages, and a nominal diameter of 8 mm about flexible
appendages 1003, particular embodiments of the present invention
include other diameters. The diameter and/or shape of the flexible
backplate 1000 in any of the aforementioned regions can be
independently tailored to a particular eye geometry, in accordance
with certain embodiments of the present invention.
[0058] FIG. 11 shows a stress-strain simulation of the
keratoprosthesis apparatus of FIG. 10. FIG. 11 shows the variation
in deformation of the flexible backplate 1000 under the application
of deforming force 1101. The flexible backplate 1000 deforms from
position 1000a to position 1000b, experiencing generally greater
deformation as you move radially outward from the tabs 1002 to the
flexible appendages 1003 and 1013. For example, the flexible
appendages 1003 and 1013 experiences the greatest amount of strain
at their outermost edge. In view of the radial position of the
appendages, they have a significant amount of flexibility.
[0059] Embodiments of the present keratoprosthesis described herein
can be implanted in different ways. In some implementations, the
eye of the patient will undergo anterior lamellar keratoplasty,
manual or femtosecond laser assisted. The excised corneal tissue
(approx. 8 mm diameter) will be trephined centrally (approximately
3 mm diameter). An optical stem, such as the optical stem 202, will
be inserted into the trephined tissue and secured with a flexible
titanium backplate, such as flexible backplate 100. The assembled
corneal tissue, optical stem, and flexible backplate will then be
placed back on top of the Descemet membrane of the eye of a
patient, and sutured around with interrupted or running suture
(similar to penetrating keratoplasty).
[0060] In other implementations, the excised corneal tissue is
discarded and a corneal donor graft is used instead, as described
above (with or without the Descemet's membrane). An optical stem,
such as the optical stem 202, will be inserted into the donor graft
and secured with a flexible titanium backplate, such as flexible
backplate 100. The assembled corneal tissue, optical stem, and
flexible backplate will then be placed on top of the Descemet
membrane of the eye of a patient and sutured, as previously
described.
[0061] In other implementations, an eye of a patient will undergo a
standard penetrating keratoplasty (full thickness). A deep anterior
lamellar keratoplasty will then be performed on a donor corneal
tissue. The anterior corneal donor tissue will be trephined and an
optical stem, such as the optical stem 202, will be fitted and
secured with a flexible titanium backplate, such as flexible
backplate 100. The assembled graft, optical stem, and flexible
backplate will then be placed on the donor's corneal bed and
sutured as previously described. A larger diameter trephine will be
used cut the donor tissue with the assembled optical stem, and
flexible backplate. The tissue will then be placed and sutured in
the eye of a patient, using standard penetrating keratoplasty
procedures.
[0062] In some other implementations, the optical stem 202, will be
fitted and secured with the flexible backplate 100 and will be
implanted in the eye of a patient as performed traditionally with
the Boston keratoprosthesis (i.e., a full thickness penetrating
keratoplasty will be performed on the patient's eye and a donor
corneal graft (full thickness) will undergo central trephination
and fitting of the flexible backplate 100 (the tissue may or may
not include the Descemet membrane of the donor). The assembled
donor corneal graft and flexible backplate 100 will then be sutured
to the patient's eye as full thickness penetrating
keratoplasty.
[0063] The surgical implantation implementations disclosed herein
may also be performed using engineered corneas or constructs, made
of human or animal collagen, polymer, or other synthetic or
biologic materials in accordance with embodiments of the present
invention. In addition, donor xenograft tissue from animal or other
parts of the human tissue can be used as tissue carriers to perform
the above surgical implantation implementations.
[0064] Various processes and logic flows described in this
specification, such as actuation of a shape memory allow of a
flexible backplate, can be performed by one or more programmable
processors executing one or more computer programs to perform
actions by operating on input data and generating output. The
processes and logic flows can also be performed by, and apparatus
can also be implemented as, special purpose logic circuitry, e.g.,
a FPGA (field programmable gate array) or an ASIC (application
specific integrated circuit).
OTHER EMBODIMENTS
[0065] While this specification contains many specific
implementation details, these should not be construed as
limitations on the scope of any inventions or of what may be
claimed, but rather as descriptions of features specific to
particular implementations of particular inventions. Certain
features that are described in this specification in the context of
separate implementations can also be implemented in combination in
a single implementation. Conversely, various features that are
described in the context of a single implementation can also be
implemented in multiple implementations separately or in any
suitable sub combination. Moreover, although features may be
described above as acting in certain combinations and even
initially claimed as such, one or more features from a claimed
combination can in some cases be excised from the combination, and
the claimed combination may be directed to a sub combination or
variation of a sub combination.
[0066] While this specification contains many specific
implementation details, these should not be construed as
limitations on the scope of any inventions or of what may be
claimed, but rather as descriptions of features specific to
particular implementations of particular inventions. Certain
features that are described in this specification in the context of
separate implementations can also be implemented in combination in
a single implementation. Conversely, various features that are
described in the context of a single implementation can also be
implemented in multiple implementations separately or in any
suitable sub combination. Moreover, although features may be
described above as acting in certain combinations and even
initially claimed as such, one or more features from a claimed
combination can in some cases be excised from the combination, and
the claimed combination may be directed to a sub combination or
variation of a sub combination.
[0067] The orientation of various elements may differ according to
other exemplary implementations, and such variations are
encompassed by the present disclosure. Features of the disclosed
implementations can be incorporated into other disclosed
implementations.
[0068] While various inventive implementations have been described
and illustrated herein, a variety of other means and/or structures
for performing the function and/or obtaining the results and/or one
or more of the advantages described herein are, and each of such
variations and/or modifications is, deemed to be within the scope
of the inventive implementations described herein. The foregoing
implementations are presented by way of example only and that,
within the scope of the appended claims and equivalents thereto,
inventive implementations may be practiced otherwise than as
specifically described and claimed. Inventive implementations of
the present disclosure are directed to each individual feature,
system, article, material, kit, and/or method described herein. In
addition, any combination of two or more such features, systems,
articles, materials, kits, and/or methods, if such features,
systems, articles, materials, kits, and/or methods are not mutually
inconsistent, is included within the inventive scope of the present
disclosure.
[0069] Also, the technology described herein may be embodied as a
method, of which at least one example has been provided. The acts
performed as part of the method may be ordered in any suitable way.
Accordingly, implementations may be constructed in which acts are
performed in an order different than illustrated, which may include
performing some acts simultaneously, even though shown as
sequential acts in illustrative implementations.
[0070] The claims should not be read as limited to the described
order or elements unless stated to that effect. It should be
understood that various changes in form and detail may be made by
one of ordinary skill in the art without departing from the spirit
and scope of the appended claims. All implementations that come
within the spirit and scope of the following claims and equivalents
thereto are claimed.
* * * * *